Estimated prevalence and genetic diversity of Bartonella species in small mammals in Europe: Systematic review and meta-analysis

Bartonellosis is a neglected vector-borne zoonotic disease caused by <i>Bartonella</i> species that infect a wide array of mammals. The adaptation of <i>Bartonella</i> to various animal hosts, including small mammal populations, has been reported, indicating their potential as a significant reservoir harboring a high genetic diversity of these pathogens, thereby posing a risk for zoonotic transmission to humans through close ecological or physical contact. Thus, this study aimed to give an overview of the prevalence and the genetic diversity of <i>Bartonella</i> spp in small mammals throughout Europe. Consequently, a systematic review was undertaken by retrieving all relevant articles indexed in PubMed, Scopus and Web of Science. Subsequently, a meta-analysis was performed to compute the pooled prevalence of <i>Bartonella</i> spp. Moreover, subgroup moderator analyses were then performed, examining the impact of sub-European region, sample type, gender, and small mammal species on the observed prevalence estimates. A total of 76 studies were included in this study. The estimated pooled prevalence of <i>Bartonella</i> spp across small mammal populations in Europe was 30%. Notably, regional analysis revealed significant variations, with the highest prevalence observed in the Eastern region (43%). At the country level, Russia had the highest pooled prevalence of 65%, while Austria had the lowest estimated prevalence (5.7%). Although variations were observed in <i>Bartonella</i> spp prevalence among subgroups, this difference was not statistically significant (p-value > 0.05). A high diversity of <i>Bartonella</i> spp was observed in European small mammals with twenty-one <i>Bartonella</i> species detected, and nine of them being pathogenic to humans. The present study offers a comprehensive understanding of the eco-epidemiology of <i>Bartonella</i> spp in small mammal in Europe, providing insight into their role as reservoirs and potential vectors in the maintenance and transmission of <i>Bartonella</i> species.